1. Field of the Invention
The present invention relates to Tandem Connection Monitoring (TCM) technology in a Multi-Protocol Label Switching (MPLS) network, and more particularly, to a TCM method for detecting the exact location of an area where an error has occurred by newly measuring performance quality of a network, regardless of the performance quality measured in a preceding network to make clear what is responsible for the error when performance of a Label Switched Path (LSP) is degraded or an error occurs.
This work was supported by the IT R&D program of MIC/IITA[2006-S-064-01, “BcN Network Engineering”].
2. Description of the Related Art
Tandem Connection Monitoring (TCM) is a technology that has been applied to Optical Transport Hierarchy (OTH) apparatuses. The technology can perform quality monitoring at a user level, a service provider level, and a network provider level. Totally, there are six levels of TCM. TCM1 is used by users, and TCM2 is used by a service provider, while the remaining TCM3 to TCM6 are used by a network provider.
An OTH apparatus includes an optical domain and a digital domain. The digital domain adopts a TCM function. The digital domain is composed of an Optical Channel Transport Unit (OTU), an Optical Channel Data Unit (ODU), and an Optical Channel Payload Unit (OPU). TCM information is carried in an overhead of the ODU and it is formed of a total of 18 bytes, three bytes per TCM. The OTH apparatus independently stores a Trail Termination Source Identifier (TTSI) value for a section to be monitored in a TCM, and monitors desired sections at a user level, a service provider level, and a network provider level, respectively.
Meanwhile, the performance of TCM is measured by checking parity errors. A transmitter calculates parities for payload of an ODU, which is OPU, based on Byte Interleaved Parity 8 (BIP-8), and transmits the result carried in a corresponding TCM byte of the next frame. In the mean time, a TCM receiver measures performance by calculating parities for the received OPU, and comparing the value transmitted carried in the next frame with the BIP-8 value stored in the transmitter. The performance in a desired section is monitored independently on the part of the network provider, the service provider, and the users in the above-described method.